Adjustable-bow bar or roll axle

Abstract

An adjustable-bow bar or roll axle, useful for spreading slit sheets of paper and for other purposes, includes a hollow cylindrical shell. Two tension bolts extend along axes parallel to the centerline of the shell, and interconnect the ends of the bar or axle. One of the bolts lies in a plane of desired curvature of the bar and applies a bending moment to curve the bar in this plane; this bolt may be located inside or outside the shell, depending on the required bending moment. The second bolt may be inside the shell; its angular position is adjustable with respect to that of the first. This bolt is set in the plane of a resultant force applied to the bar by the tension in the sheet, and applies a bending moment to offset this force and prevent curvature of the bar in this plane. A third bolt may be located in a vertical plane to apply a bending moment to prevent curvature of the bar by its weight; or the second bolt may serve this purpose also.

What I claim is: 
     
       1. An adjustable-bow device having an arcuate outer surface portion adapted for wrapping by an indefinite length of sheet material wrapped partially thereabout, said device comprising a hollow cylindrical shell having a major longitudinal axis, and means for supporting said shell with a predetermined angular orientation; first means for applying adjustable longitudinal stress to said shell along a first axis parallel to and spaced apart from said major axis, said first stress-applying means being constructed and arranged to bow said shell parallel to a first plane defined by said first axis and said major axis;   said shell being subject to a resultant force applied to said shell and lying in a second plane defined by said major axis and a second axis parallel to and spaced apart from said major axis, said resultant force tending to induce undesired curvature in said shell parallel to said second plane;   and second means constructed and arranged for applying adjustable longitudinal stress to said shell in said second plane and in opposition to said resultant force to remove said undesired curvature from said shell.   
     
     
       2. An adjustable-bow device as recited in claim 1, said first and second stress-applying means being relatively angularly adjustable with respect to one another about said major axis. 
     
     
       3. An adjustable-bow device as recited in claim 1, at least one of said stress-applying means being angularly adjustable about said major axis with respect to said shell. 
     
     
       4. An adjustable-bow device as recited in claim 1, said first and second stress-applying means being independently angularly adjustable about said major axis with respect to said shell. 
     
     
       5. An adjustable-bow device as recited in claim 1, together with third means for applying longitudinal stress to said shell along a third axis parallel to and spaced apart from said major axis, said third axis lying in a vertical plane passing through said major axis, and being constructed and arranged to remove curvature induced in said shell by the weight thereof. 
     
     
       6. An adjustable-bow device as recited in claim 1, said shell being provided with end caps, at least one of said stress-applying means comprising a tension bolt passing through said end caps. 
     
     
       7. An adjustable-bow device as recited in claim 6, said end caps and said bolt being jointly angularly movable relative to said shell to relocate said second plane. 
     
     
       8. An adjustable-bow device as recited in claim 6, the other of said stress-applying means comprising a second tension bolt exterior to said shell and a pair of arms attached to opposite end portions of said shell, extending radially therefrom, and attached outwardly from said shell to opposite end portions of said second bolt. 
     
     
       9. An adjustable-bow device as recited in claim 1, said shell being provided with end caps, said first and second stress-applying means comprising tension bolts passing through said end caps, said end caps being formed with arcuate slots receiving one of said stress-applying bolts, said slots being generated by circular arcs about said major axis; whereby said first and second planes may be relatively angularly displaced by moving said one stress-applying bolt without angular displacement of said shell and the other said stress-applying bolt. 
     
     
       10. An adjustable-bow device as recited in claim 9, together with a pair of sealing plates for said slots, said sealing plates being supported on said one stress-applying bolt and being movable therewith to hermetically seal said slots. 
     
     
       11. An adjustable-bow device as recited in claim 8, together with means for sealing said slots against the escape of air therefrom, said arcuate outer surface portion of said shell being formed with a plurality of air holes, whereby air supplied to the interior of said shell passes through said holes to form an air cushion between said shell and said sheet material. 
     
     
       12. An adjustable-bow device as recited in claim 1, said supporting means mounting said shell and said first stress-applying means for joint angular displacement about said major axis of said shell, and including means for angularly adjusting said shell and said first stress-applying means to relocate said first plane. 
     
     
       13. An adjustable-bow device as recited in claim 12, said second stress-applying means being angularly adjustable independently of said shell and said first stress-applying means to relocate said second plane.